Method of making compound pinion gear

ABSTRACT

A compound planetary gearset in which the input ring gear drives the large pinion of a compound planetary pinion and the low brake holds the large sun gear meshing with the small pinion, the second brake holds the small sun gear meshing with the large pinion and the direct drive clutch locks the small sun gear to the output shaft and the reverse brake holds a second ring gear which meshes with a reverse pinion, also meshing with the large sun gear. The small pinion and the large pinion of the compound pinion have the same number of teeth. The small pinion has a small pitch and the gears meshing with it the same small pitch, and the large pinion has a large pitch and the gears meshing with it have the same large pitch. The compound pinions are finish cut by a one piece cutter which simultaneously cuts a pair of teeth, one tooth on the large pinion and one tooth on the small pinion, so the teeth on both pinions of each compound pinion have an identical radial alignment relation to each other and all the compound pinions of the gearset are identical in this relation for equal load sharing.

Dec. 11, 1973 1 METHOD OF MAKING COMPOUND HNEON GEAR [75] Inventor: Oliver K. Kelley, Bloomfield Hills,

Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

{22] Filed: July 28, 1972 [21] App]. No.1276,065

Related ()5. Application Data [62] Division of Ser. No. 82,599. Oct. 21, 1970, Pat. No

{52} US. Cl 90/10, 29/1592, 90/7.5, 90/8 [51] Int. Cl B231 1/04 [58] Field of Search 90/7, 7.5, 8, 10; 29/1592 [56] References Cited UNITED STATES PATENTS 3,251,271 5/1966 Witte et a1. 90/7.5

Primary ExaminerFranCis S. Husar Atr0rneyW. E. Finken et al.

[57] ABSTRACT A compound planetary gearset in which the input ring gear drives the large pinion of a compound planetary pinion and the low brake holds the large sun gear meshing with the small pinion, the second ,brake holds the small sun gear meshing with the large pinion and the direct drive clutch locks the small sun gear to the output shaft and the reverse brake holds a second ring gear which meshes with a reverse pinion, also meshing with the large sun gear. The small pinion and the large pinion of the compound pinion have the same number of teeth. The small pinion has a small pitch and the gears meshing with it the same small pitch, and the large pinion has a large pitch and the gears meshing with it have the same large pitch. The compound pinions are finish cut by a one piece cutter which simultaneously cuts a pair of teeth, one tooth on the large pinion and one tooth on the small pinion, so the teeth on both pinions of each compound pinion have an identical radial alignment relation to each other and all the compound pinions of the gearset are identical in this relation for equal load sharing.

2. Claims, 5 Drawing Figures METHOD OF MAKING COMPOUND IPINION GlEAlR This is a division of application, Ser. No. 82,599 filed Oct. 21, 1970 and now US. Pat. No. 3,721,135.

This invention relates to transmission gearing and particularly to manufacturing of compound planetary pinions.

While transmissions having integral compound pinions, and an integral pinion having two or more different diameter pinion gears, have been proposed, they have not been commercially used in high production power transmissions because of the difficulty of manufacturing compound gears with sufficient accuracy and alikeness for proper load sharing by each of the compound pinions.

The invention is directed to planetary gearing having a plurality of compound pinions in which each of the unitary compound pinions has a small diameter pinion gear and a large diameter pinion gear having the same number of gear teeth. The small pinion has small pitch gear teeth and the large pinion has large pitch gear teeth. The sun and ring gears have the same pitch as the pinion with which they mesh. A unitary or one-piece cutter assembly is employed to simultaneously make the final cut or shave on a large pinion tooth and a small pinion tooth of the compound pinion, so that both the small and the large pinion teeth will have an identical radial alignment relation to each other and the compound pinions will be identical in this relation for equal load sharing. The gear unit provides low ratio when the large sun gear meshing with the small pinion is held. Then the input ring gear drives the large pinion to drive the carrier at a low ratio. For second ratio, the small sun gear meshing with the large pinion is held, and the input ring gear drives the large pinion and carrier at intermediate speeds. For third ratio, the direct drive clutch connects the small sun gear and the carrier output so the input ring gear drives the carrier at 1:1 drive. For reverse, the reverse ring gear is held which, through the interaction of the reverse pinion meshing with the large sun gear and the compound pinion, provides, when the input driven ring gear drives the compound pinion, reverse drive of the output carrier.

An object of the invention is to provide an improved compound planetary pinion gearset to provide equal load sharing by the compound pinions.

Another object of the invention is to provide a compound planetary pinion gearset having a compound pinion gear having the same number of teeth on the large and small diameter pinion gears and the teeth thereof having a pitch proportional to the diameter.

Another object of the invention is to provide a compound planetary pinion gearset having a plurality of compound pinions each having a large diameter and pitch pinion gear and a small diameter and pitch pinion gear each meshing with a central gear having the same number of teeth with each tooth on one pinion gear and a paired tooth on the other pinion gear simultaneously cut by a unitary cutter for an identical radial alignment relationship of the teeth on one gear to the teeth on the other gear of each compound pinion to equalize the load on the compound pinions.

Another object of the invention is to provide a compound planetary pinion gearset having a compound planetary pinion having a large diameter pinion gear meshing with an input ring gearand an intermediate speed reaction sun gear, the small diameter pinion gear pinion gear meshing with a small pitch low speed reaction sun gear and a small pitch reverse pinion gear meshing with the low speed reaction gear and a small pitch reverse reaction ring gear.

Another object of the invention is to provide for a compound planetary transmission. a compound planetary pinion having a large and small diameter pinion with the same number of small and large pitch teeth respectively and the teeth being simultaneously cut by a unitized cutter reciprocating on one axis to assure that the teeth of both pinion gears have the same radial alignment relationship to each other and that all the compound pinions are identical in this relationship for substantially equal load sharing.

Another object of the invention is to provide a method of making compound pinion gears in which the rough cut compound pinion having the same number of teeth on the large and small diameter pinion gears is finish cut by a unitary cutter having one cutter to cut the teeth of the large pinion gear and a second cutter to cut the teeth of the small pinion gear and is moved on an axis of a machine to simultaneously finish cut during the same stroke of the cutter a tooth on the large gear and a tooth on the small gear so these teeth have the same radial alignment relation to each other.

These and other objects of the invention will be more apparent from the following description and drawing of a preferred embodiment.

FIG. 1 schematically shows the gearing arrangement.

FIG. 2 is a partial sectionof FIG. 1 on the line 22.

FIG. 3 is a detail view of the compound pinion.

FIG. 41 is a partial end view of the compound pinion.

FIG. 5 schematically shows the compound pinion and the cutters positioned for cutting the compound pinion.

The transmission gearing shown in FIG. 1 has an input shaft 10, preferably driven by a torque converter and driving through the disc 11 the input ring gear 12 of the planetary gear unit. The large pinion gear 141 of each of the compound pinions 16 meshes with the ring gear 112 and the sun gear 17 which is connected by a sleeve shaft 13 to the control described below. Each compound pinion 16 also has an integral small pinion gear 19 which meshes with reaction sun gear 21 connected to the control sleeve 22. The reverse pinion 23 meshes with sun gear 21 and internal ring gear 241 but not with the compound pinion. Three or four sets, each having a reverse pinion 23 and a compound pinion 16, are rotatably mounted by suitable bearings, such as needle hearings, on their respective pinion shafts 26 and 27 which are part of a carrier assembly 28 which drives the output shaft 29. The ring gear 24 has a brake drum portion 31 which may have an internal bearing portion 32 and is suitably mounted by a bearing 33 on a sleeve portion 34 projecting from a central wall 35 of the housing 36. The reverse brake band 37 cooperates with the reverse brake drum 31 to hold the ring gear 24-. The low brake drum 38 is drivingly connected by the disc portion thereof to the control sleeve shaft 22 and axially located by a thrust bearing 39 between the drum hub 40 and the transmission wall 35. The low brake band 41 cooperates with the low drum 38 to hold the sun gear 21. The sun gear 17 is connected by the sleeve shaft 18 to the disc 42 of the second speed brake drum 43 which is held by the second speed brake band 44 for second speed. The above brake bands are operated by conventional fluid motors which engage and disengage the rection brake bands with their respective drums. The direct drive or third clutch 46 has alternate plates splined to the internal surface of drum 43 and intermediate plates splined to the inner drum 47 drivingly connected to the output shaft 29. A cylinder member 48 is secured to the side of drum 43 opposite disc 42 and has an inner cylindrical portion 49 providing an annular cylinder to receive the annular piston 51 between the inner cylindrical portion and the drum. The housing 36 has a rear wall 52 having a cylindrical portion 53 within the cylindrical portion 49 providing a fluid transfer device to supply fluid from a passage 54 in the housing to the space 56 between the housing, the hub of inner drum 47, the transfer passages 57 in the housing and the passage 58 in the rotary cylinder member 48 to supply fluid to the expansible chamber or cylinder therein to engage the clutch. Suitable retraction springs, not shown, disengage the clutch.

Suitable bearings 62 rotatably supporting shaft 22 on the housing and bearings 63 and 64 supporting sleeve shaft 18 on sleeve shaft 22 may be provided. Thrust bearings, 39,65 and 66, will axially locate the elements.

Engagement of the brake 41 holds the sun gear 21 so the input ring gear 12 drives the carrier 28 and output shaft 29 in the low speed ratio. Engagement of the brake 44 holds the sun gear 17 so the input driven ring gear 12 drives the carrier 28 and output shaft 29 at the second or intermediate speed ratio. Engagement of the clutch 46 locks the sun gear 17 to the output shaft so the input ring gear 12 provides a third speed or 1:1 drive. Engagement of the brake 37 holds the ring gear 24 which, through the interaction of the reverse pinion 23, sun gear 21, and the compound pinion 16, provides when the input ring gear 12 is driving, a reverse drive of the carrier 28 and the output shaft 29. The brake bands and clutch are actuated by suitable servo motors and the clutch and brakes are selectively hydraulically actuated by known fluid controls of the automatic or semi-automatic type.

The compound planetary pinion is a one-piece or integral stepped pinion having a large diameter gear portion 14 of narrow width and a small diameter gear portion having a larger width for equal torque capacity. Both the small diameter pinion 19 and the large diameter pinion 14 have the same number of teeth and thus the small pinion will have small pitch teeth and the large pinion will have large pitch teeth directly proportional to their diameter and circumference. The compound pinion gears 14 and 19 on the compound pinion are rough cut by milling, shaping or hobbing on conventional gear cutting machines. When the finish cut is made on these machines in the conventional manner by separate cutters operating simultaneously or sequentially, the drive mechanism or the mechanism for determining the alignment relationship of the teeth on one gear to the teeth on the other gear, respectively, will result in tolerance variations in the radial alignment relationship of the teeth on one pinion gear to the teeth on the other pinion gear and thus a lack of alikeness or identicalness of each compound pinion. While compound gears having both the rough and finish cuts made by these conventional production methods are satisfactory for other gearing arrangements, the small inaccuracies or tolerance variations, i.e. 0.002 inch, in the radial alignment relationship of the teeth on one pinion gear to the teeth on the other pinion gear of each compound pinion and the lack of alikeness or identicalness of this relationship of the three or four compound pinions in a planetary gear set prevent proper equalized load sharing by the pinions.

In this compound planetary gear set the critical condition occurs in low ratio drive when reaction brake 41 is engaged to hold sun gear 21. Then the input ring gear, a central gear, drives pinion gear 14 through the contacting and loaded teeth and the pinion gear 19 reacts on fixed sun gear 21, a central gear, through the contacting and equally unit loaded teeth. Thus for equalized load sharing, each compound pinion must have a tooth on the large pinion l4 contacting a tooth on the ring gear and a tooth on the small pinion gear 19 contacting a tooth on the sun gear 21. This requires a high degree of accuracy of the relative radial angular position of the teeth on the small pinion gear relative to the large pinion gear of each compound pinion in the planetary gear set. Thus, in order to obtain equalized load sharing by the compound pinions of a compound pinion planetary gear set thee radial angular relationship of the teeth on the small pinion gear 19 to the teeth on the large pinion gear 14 must be the same or identical in each of the compound pinions.

In order to obtain this high degree of accuracy of the relative radial angular position of the teeth on both pinion gears, at least a pair of teeth, one tooth of each pinion gear, are simultaneously finish cut by a unitized cutter moving in the same cutting stroke. In compound pinion 16 in this gear set, the loaded tooth of pinion gear 14 is diametrically opposite the loaded tooth of pinion gear 19. While a unitized cutter, like cutter tool with facing cutters, could be used to simultaneously finish cut in pairs these two loaded teeth on opposite sides of the compound pinion, a simpler cutter tool 75, for simultaneously cutting two substantially aligned teeth, one on each pinion gear, will provide the desired degree of accuracy. The rough cut compound pinion is fixed on, or clamped on, a conventional indexing rotary work holder or arbor 71 of a gear shaping machine. A shaper, either vertical or horizontal, having a work or gear holding table or arbor which accurately indexes one tooth space at a time to position each tooth in cutting positions for finish cutting or shaving by a tool formed to cut a single tooth mounted on a tool head reciprocated on an axis parallel to the arbor axis is used. A gear shaper machine like the G. Fisher U.S. Pat. No. 2,246,671 issued June 24, 1941, the E.W. Miller U.S. Pat. No. 2,372,596 issued Mar. 27, 1945 and similar commercially available gear shaper machines may be used. A unitary or one-piece cutter tool 75 having cutter 72 for pinion gear 19 and cutter 73 for pinion gear 14 is mounted on the reciprocating cutter head and when the compound pinion 16 is indexed in cutting position, the reciprocating cutter head moves in a cutting stroke and as shown cutter 73, having a cutter shape 73a to finish cut the adjacent faces of two adjacent teeth of pinion gear 14 and cutter 72 having a similar cutter shape to finish cut the adjacent faces of two adjacent teeth of pinion gear 19 simultaneously initiate and move through a cutting stroke finish cutting these aligned gear tooth contact surfaces in identical radial alignment relation to each other. Both cutters may also be shaped as at 73b to cut both sides of the same tooth.

The recess 74 between the teeth of the pinion gears 14 and 19 provides clearance for the cutter 72 to finish the teeth of gear 19 to the end adjacent gear 1 1. Both cutters 72 and 73 are fixed on one cutter tool member 75 which is mounted on a reciprocating cutter head of a gear shaper for reciprocating movement in the gear shaper to simultaneously cut pairs of contact surfaces, at least one surface on each gear of the compound pinion 16. Since the indexing mechanisms are very accurate and a single unitary cutter tool or member, having two cutters mounted in fixed peripheral relationship thereon, simultaneously or in the same operating stroke cuts a contact surface on the teeth of both the small pinion gear 19 and the large pinion gear 14, the gear teeth, especially their contact surfaces, of each pinion gear of the compound pinion 16 will be more accurately peripherally related to each other or have identi cal radial angular alignment relationship to each other and each compound pinion will have this identical relationship, since they are cut by the same cutter, for simultaneous tooth engagement of one pinion gear with meshing ring gear and the other pinion gear with the meshing sun gear of all the compound pinions of each gearset so they equally share the load. It is important that the gears have the same number of teeth and that the same number of corresponding tooth contact surfaces on both the large and small pinion gears be cut at the same time for identity of angular relation of the surfaces of all gears on each compound pinion and all compound pinions. Thus the compound pinions have all the contact surfaces consisting entirely of corresponding pairs of concurrently co-formed identical angularly related contact surfaces, at least one on the small pinion gear and one on the large pinion gear, and each pinion has identical angularly related contact surfaces for equal load sharing. Other dimensions of the compound pinions may have the normal larger tolerance variations.

Since gear machine indexing devices are quite accurate and the tolerance variations thereof are very consistent from gear to gear, such tolerance variations have very little adverse effect on equalized loading because each compound pinion and both pinion gears will have substantially the same tolerance variation from the indexing device.

While the centerlines of the teeth of the large and small pinions of each compound pinion may be radially aligned, the centerlines of the teeth of one may be peripherally displaced a small distance with respect to the centerlines of the teeth of the other uniformly for all compound pinions so the gear impact frequency and significant harmonics thereof of both pinion gears and their meshing central gears, i.e., sun and ring gears, are out of phase. The pinion axis spacing may also be varied for noise reduction.

It will be appreciated that modifications may be made of the above disclosed invention.

1 claim:

1. A method of manufacturing compound pinions having a large pinion gear and a small pinion gear each having the same number of teeth; the compound pinion is secured coaxially to a rotary indexing member which accurately rotatively indexes the compound pinion to each of a plurality of gear cutting positions; securing the compound pinion on the rotary indexing member secured in one gear cutting position, a relatively axially reciprocating unitary cutter having a cutter edge to cut at least one contact surface on the small pinion and a cutter edge to cut the corresponding contact surface on the large pinion and moves parallel to the contact surface and during only relative reciprocation cuts corresponding tooth surfaces on each pinion gear, at least one tooth contact surface on the small pinion gear and the corresponding tooth contact surface on the large pinion gear simultaneously during the same relative reciprocating stroke and establishes an identical radial alignment relation between the corresponding simultaneously cut contact surfaces on the large and small pinion, rotatably re-indexing the indexing member to rotate the gear to other gear cutting positions and simi' larly cutting all tooth contact surfaces.

2. A method of manufacturing compound pinions having a large pinion gear and a small pinion gear each having the same number of teeth; the compound pinion is secured coaxially to a rotary indexing member which accurately rotatively indexes the compound pinion to and secures it in each of a plurality of gear cutting positions; with the compound pinion secured against rotation and in one gear cutting position, a relatively reciprocating unitary cutter having a cutter edge to cut at least one contact surface on the small pinion and a cut ter edge to cut the corresponding contact surface on the large pinion and moves on an axis parallel to the gear axis and during only relative reciprocation cuts corresponding tooth surfaces on each pinion gear, at least one tooth contact surface on the small pinion gear and the corresponding tooth contact surface on the large pinion gear simultaneously during the same relatively reciprocating axial stroke and establishes an identical radial alignment relation between the corresponding simultaneously cut contact surfaces on the large and small pinion, and similarly rotatably reindexing the indexing member to rotate and secure the gear in other gear cutting positions and similarly cutting all tooth contact surfaces.

I Page 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Oliver K. Kelley Inventor(s) 7 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Sheet 2 of the drawings as shown attached should be included.

Signed and sealed this 17th day of December 1974.

(SEAL) Attest:

3'-'[cCOY M. GIBSON C. MARSHALL DANN attesting Officer Commissioner of Patents )RM PO-1050(10-69) V USCOMM'DC 6037$-P59 U.S. GOVERNHENT PRINTING OFFICE: 869. 930

Patent No.

Dated December 11, 1975 Invent0r(s) Oliver K. Kelley It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

l Mane m li P .h M MA K FORM 040 33,? u-WM.-. M-

- AM-DC scan-pus U S GOVCRNMIK'! 'RIKYING OFFICE B694 930 

1. A method of manufacturing compound pinions having a large pinion gear and a small pinion gear each having the same number of teeth; the compound pinion is secured coaxially to a rotary indexing member which accurately rotatively indexes the compound pinion to each of a plurality of gear cutting positions; securing the compound pinion on the rotary indexing member secured in one gear cutting position, a relatively axially reciprocating unitary cutter having a cutter edge to cut at least one contact surface on the small pinion and a cutter edge to cut the corresponding contact surface on the large pinion and moves parallel to the contact surface and during only relative reciprocation cuts corresponding tooth surfaces on each pinion gear, at least one tooth contact surface on the small pinion gear and the corresponding tooth contact surface on the large pinion gear simultaneously during the same relative reciprocating stroke and establishes an identical radial alignment relation between the corresponding simultaneoUsly cut contact surfaces on the large and small pinion, rotatably re-indexing the indexing member to rotate the gear to other gear cutting positions and similarly cutting all tooth contact surfaces.
 2. A method of manufacturing compound pinions having a large pinion gear and a small pinion gear each having the same number of teeth; the compound pinion is secured coaxially to a rotary indexing member which accurately rotatively indexes the compound pinion to and secures it in each of a plurality of gear cutting positions; with the compound pinion secured against rotation and in one gear cutting position, a relatively reciprocating unitary cutter having a cutter edge to cut at least one contact surface on the small pinion and a cutter edge to cut the corresponding contact surface on the large pinion and moves on an axis parallel to the gear axis and during only relative reciprocation cuts corresponding tooth surfaces on each pinion gear, at least one tooth contact surface on the small pinion gear and the corresponding tooth contact surface on the large pinion gear simultaneously during the same relatively reciprocating axial stroke and establishes an identical radial alignment relation between the corresponding simultaneously cut contact surfaces on the large and small pinion, and similarly rotatably re-indexing the indexing member to rotate and secure the gear in other gear cutting positions and similarly cutting all tooth contact surfaces. 